Biology subjects

Almela, P.

Publications and source records attributed to Almela, P..

3 recordsLinked to original sources

bioRxiv2025

Taxonomy-driven variations in snow algae color modulate albedo and energy balance in a single snow patch

In this study, we examined the reflectance, pigment composition, and community composition of three snow algae blooms showing distinct colors in the same snowfield in Glacier National Park (USA). Each color bloom was dominated by a different algae, each exhibiting a unique pigment signature but with astaxanthin as the predominant pigment across all three blooms. The spectral reflectance of red snow algae was consistently lower than that of green algae, while orange algae had intermediate reflectance values. Specifically, red algae reduced reflectance by approximately 55% across the PAR range, while green algae reduced reflectance by 25%. Red algae also demonstrated the highest radiative forcing, double that of green algae, leading to increased energy re-emission into the surrounding environment, which likely contributes to the localized melting of adjacent ice crystals. The high absorbance around 680 nm in cells with high astaxanthin content, such as the orange algae, suggests that semi-automatic detection methods could effectively identify these algae, as their spectral features remain distinct despite the presence of secondary carotenoids. Our data demonstrate the impact of snow algae taxonomic and pigment composition on the radiative balance of snowfields, underscoring taxonomy as a key determinant of bloom color under similar environmental conditions

microbiology↗

bioRxiv2025

Enhancing DNA recovery in low-biomass snow algae samples: a comparative study of extraction methods and their effect on community composition

High-throughput sequencing is a powerful tool for environmental microbiology and can be particularly important for examining community structure and function for organisms that are difficult to culture or environments that are difficult to mimic like snow algae. DNA extraction significantly impacts these analyses, often introducing more variation than PCR or sequencing. Snow algae are widespread on mountain and polar snowfields where they contribute to biogeochemical cycling and accelerate melt. Despite increasing research on snow algae, inconsistencies in DNA extraction remain a major challenge, and no recommended method exists for assessing their community composition and richness. Here, we compared three common extraction methods (DNeasy PowerSoil Pro, DNeasy PowerWater, and phenol-chloroform) alongside ultrasonication in samples with varying snow algae abundance. The extraction method strongly influenced resulting microbial profiles assessed by amplicon sequencing of rRNA genes. Ultrasonication improved DNA yield in low-biomass samples and enhanced the recovery of resilient cells, including mature-phase snow algae likely due to improved cell lysis step. This is the first systematic comparison of DNA extraction methods for snow algae, highlighting how methodological choices affect microbial community analyses. Our findings provide insights to improve standardization, enhancing the reliability of future studies in snow and ice environments.

microbiology↗

bioRxiv2024

Laboratory experiments suggests limited impact of increased nitrogen deposition on snow algae blooms

Snow algal blooms decrease snow albedo and increase local melt rates. However, the causes behind the size and frequency of these blooms are still not well understood. One factor that is likely contributing is nutrient availability, specifically nitrogen (N) and phosphorus (P). However, the nutrient requirements of the taxa responsible for these blooms is not known. Here, we assessed the growth of three commercial strains of snow algae under 24 different nutrient treatments that varied in both absolute and relative concentrations of N and P. After 38 days of incubation, we measured total biomass and cell size and estimated their effective albedo reduction surface (EARS). Snow algal strains tended to respond similarly and achieved bloom-like cell densities over a wide range of NP conditions. However, the molar ratio of N:P at which maximum biomass was achieved was between 4 and 7. Our data indicate a high requirement for P for snow algae and suggest that additional N inputs into the ecosystem may not significantly impact the productivity and abundance of snow algae blooms. This highlights P availability as a critical factor influencing the frequency and extent of snow algae blooms and their potential contribution to snow melt through altered albedo.

microbiology↗